18 BULLETIN 352, U. S. DEPAETMENT OF AGEICULTUEE. 



The proportion of sexes under natural conditions was not deter- 

 mined, but among those reared in the life-history cages the males 

 and females appeared in almost exactly equal numbers, there being 

 282 males and 281 females. 



SEASONAL-HISTORY SUMMARY. 



The cherry leaf-beetle hibernates in the adult stage. The beetles 

 emerge from their winter quarters in the late spring, and, after feed- 

 ing for a few weeks and mating, the females go to the bases of the 

 trees and deposit their eggs in the accumulation of rubbish. In some- 

 thing less than two weeks the eggs hatch. The larvae grow rapidly 

 and in less than two weeks attain full growth, when they burrow a 

 short distance into the ground, pass thi'ough their pupal stage, and, 

 in from two to tlu-ee weeks after entering the ground, reappear as 

 adult beetles. These beetles feed until cold weather compels them to 

 seek shelter for the winter. 



The season of 1915 was unusually cold and wet, and this condition 

 undoubtedly delayed the development of the insect to a considerable 

 extent. The hibernating beetles appeared at North East on June 7. 

 Within two weeks their numbers were noticeably diminisliing, but 

 beetles of both sexes were observed as late as August 5, and females 

 collected at this time still contained eggs. Unfortunately the natural 

 food plant and egg-laying habits were not learned until the 3d of 

 August, but at this time many eggs were still unhatched. LarvaB 

 continued to emerge until August 14, and from another lot of eggs 

 collected August 5 larvae were hatched as late as August 18. At the 

 time these eggs were collectel there were full-grown larvae on the 

 trees, and many had undoubtedly entered the ground for pupation. 

 Larvae were observed on the pin cherry as late as September 10, when 

 a full-grown larva and a young third-stage larva were found on some 

 foUage that had been brought into the laboratory two days earlier. 

 The active feeding portion of the larval life in the cages varied from 

 10 to 20 days, the average being 12.33 days. 



The period spent in the ground in the cages varied from 14 to 28 

 days, the average being 22.36 days. The total developmental per- 

 iod is from 45 to 50 days. 



The earliest adult to emerge in the cages appeared on August 23, 

 but the pale, newly emerged beetles were observed in the open on the 

 16th. On August 31 the adults of the new brood were abundant on 

 pin cherry, while many young beetles and pupae and a few larvae were 

 found in soil and leaf mold under the bushes. On September 8 adults 

 were abundant, but by September 23 they had begun to disappear, 

 and no pupae could be found in the ground, although a few newly 

 emerged adults were observed. 



